1. Field
The embodiments relate to an electrically data rewritable nonvolatile semiconductor memory device, and a method of data write therein.
2. Background
Stacking of memory cells is expected to improve bit density in nonvolatile semiconductor memory devices such as NAND type flash memories. Proposed as an example of such a device is a stacked type NAND flash memory in which vertical transistors are used to configure memory transistors.
However, data retention characteristics in current stacked type NAND flash memories are not sufficiently high.